Searching for Deconfined QuarkMatter in HI collisions at
- Slides: 28
Searching for Deconfined Quark-Matter in HI collisions at the CERN LHC with CMS/CASTOR Nu. PECC Annual Meeting Athens, 8 October, 2010 Apostolos D. Panagiotou CMS/Athens – CASTOR group
Heavy Ion Physics at the LHC with CMS Central region Forward region
Energy & Particle Pseudorapidity Distributions 5. 5 Te. V 30% Net Baryon Number Pb+Pb @ 2. 8 Te. V All of Net Baryon Number in forward region High Baryochemical Potential Lower temperature
A
(Strangelet ? ) 1. 5 λI Hadron limit 3. 6 λI Hadron limit 3. 2 λI
What is a “Strangelet” ?
“Stable” Strangelet interaction in CASTOR MC-algorithm Strangelet is considered with radius: The rescaled r 0 is determined by the number density of the strange matter: n = A/V = (1/3)(nu+nd+ns) where ni=- ∂Ωi/∂μi; Ω(mi, μi, αs), taking into account the QCD corrections O(αs) to the properties of SQM. s s s Mean interaction path: Strangelets passing through the detector collide with W nuclei: Spectator part is continuing its passage. Wounded part produces particles in a standard way. Particles produced in successive interactions initiate electromagneticnuclear cascades. Process ends when strangelet is destroyed. E. Farhi, R. Jaffe, Phys. Rev. D 30(1984)2379; M. Berger, R. Jaffe, Phys. Rev. C 35(1987)213, G. Wilky, Z. Wlodarczyk, J. Phys. G 22(1996)L 105; E. Gładysz, Z. Włodarczyk, J. Phys. G 23(1997)2057 10
Scaled Radius & Mean Free Path of Strangelets vr μq λWπ ~ 7 cm Collapsed nucleus quark 11
MC simulation of Strangelets in CASTOR 28 -05 - 12
Characteristics of a “LFC” Event 1. Sector with much higher energy than the average: Strong azimuthal asymmetry in energy deposition 2. Strong penetration of the longitudinal cascade in a sector: Strong fluctuations in longitudinal transition curves 3. Much smaller EEM / EHAD compared to HIJING 4. Appearing in a very low multiplicity event compared to HIJING 13
CMS/CASTOR Calorimeter Side View Front View 28 -05 - 14
L. F. C. Identification Analysis Event-by-event analysis in 3 steps: σsd = standard deviation of the distribution of the energies Ei <E> = mean energy in sectors (i = 1 – 16 sectors) LFC Signatures 1 Azimuthal asymmetry in energy deposition 2 Fluctuations longitudinal transition curves energy distribution per RU average distribution Large magnitude of energy fluctuations in RUs manifest in abnormal transition curves 3 Examine Ratio EEM / EHAD of events
Analysis (Ι) “LFC signature” Azimouthal Energy distribution Cascade Energy distribution - Event-by-event - Sector-by-sector (Central Pb+Pb collisions, b=0)
Analysis (Ι) “Strangelet signature” Azimouthal Energy distribution Cascade Energy distribution - Event-by-event - Sector-by-sector (central Pb+Pb collisions, b=0) Select φ-sector containing LFC
Analysis (ΙI) Fluctuations on the (fa, fl) plane Strangelets E=6 -15 Te. V HIJING (2 k events) Statistical fluctuations of HIJING events with similar characteristics Strangelets with higher energies are separated from conventional HIJING events Distinction of conventional events with similar fluctuations EEM/EHD
Analysis (ΙII) 19
Analysis (ΙII) 20
Cross Section Estimation for LFC • Probability for a hadron-rich ‘Centauro-type’ event is about 3%, estimated from statistics of Chacaltaya and Pamir experiments for cosmic ray families with visible energy greater than 100 Te. V. • In about 10% of hadron-rich events, strongly penetrating cascades, clusters, or “halo” were observed. Assume total probability for “Long Flying Component” (LFC) production in central nucleus-nucleus collisions to be approximately: 0. 03 x 0. 1 ~ O(10− 3). • At LHC kinematics, the percent of LFCs in CASTOR phase space is at least ~ 1% of total number of LFCs produced in central Pb-Pb collisions, depending on their mass and energy (CENGEN). • An order of magnitude estimation of the total probability for LFC detection in CASTOR is: PCASTORLFC ≈ 10− 3 × 0. 01 ≈ O(10− 5) ΝLFC ~ 1 -10 in 4 wks Pb+Pb (5 M central events in 2010) 21
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